Track shunting apparatus



Sept; H. N. VAN AKEN 2,172,894

TRACK SHUNTING APPARATUS FiledFeb. 10, 1933 IN VENT 0R BY 62mm HIS ATTORNEY Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE TRACK SHUNTING APPARATUS Application February 10, 1933, Serial No. 656,138

4 Claims.

My invention relates to track shunting apparatus, and more particularly to apparatus for shunting track circuits by light weight rail vehicles having pneumatic tired wheels.

I will describe one form of track shunting apparatus embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing the track shunting apparatus as applied to an alternating current track circuit.

The apparatus for shunting of track circuits set forth in my present application is somewhat similar to that set forth in the copending application Serial No. 629,030, filed by Howard A. Thompson on August 16, 1932, for Apparatus for decreasing rail contact resistance and the said copending application contains claims which cover broadly certain features of the invention described in my present application.

In shunting a track circuit by means of an auxiliary current from a source on the car, which current is caused to flow through the rail film on the rail surface to lower the shunt resistance, it is customary to indicate the effectiveness of the track shunt being obtained by the magnitude of the auxiliary current flowing in the film breakdown circuit. Although this method is satisfactory in practice, precautions must be observed to insulate carefully certain portions of the shunting apparatus in order that an increase in the auxiliary current will not result from short circuits, or other causes. Otherwise, the car operator may continue to receive an indication that a proper shunt is being provided at a time when.

the effectiveness of the apparatus has been materially impaired.

In the circuit which-I have illustrated, the indicator on the car is made to respond not to the film breakdown current, but to shunt current 'supp1ied from the track circuit source, which source also energizes the track relay, so that when a shunt of sufficiently low impedance is established by the shunting apparatus, current of the proper magnitude from the aforesaid source will flow in the shunt path, to energize the indicator. In this manner, the car indicator becomes capable of providing more direct information as to the energized or deenergized condition of the track relay. That is, when the indicator is energized as above, it may be safely assumed that the impedance to the track circuit current of the shunt path around the relay, which impedance is depended upon for re- 55 lease and which, if sufficiently low, is practically certain to produce the desired release, is at or below a given maximum safe value.

Referring to the drawing, the track section D-E is provided at one end with a track transformer T energized from a suitable source 5 BX--CX, which feeds track circuit energy to the rails i and 2 through a current limiting reactor X. A track relay TR is provided at the other end of the section, in the usual manner. The remaining apparatus which is illustrated is in- 10 tended to be carried on the car.

The alternating current generator G, driven by the motor M which is energized from the car battery CB, supplies current through a limiting reactor X to the primary winding 3 of a 15' transformer T The frequency of the current delivered by generator G should be substantially diiferent from the frequency of the wayside source BXCX to prevent undesired interference of the current from one or the other source with the 20 operation of track relay TR, or indicating relay IR. Transformer T is provided with two secondary windings i and 5, the voltage of winding 4 being applied across rail shoes I and 8,

through winding I0 of the indication relay IR, 5.

and the voltage of winding 5 being applied across shoes 6 and 9, through winding H of the indication relay.

With windings 4 and 5 arranged to have relative instantaneous polarities as indicated on the 30 drawing, it will be apparent that these windings are series-aiding in causing a film breakdown current from generator G to flow over a path which may be traced from the plus terminal of winding 4, winding ill of relay IR, shoes I and B and the rail portion therebetween, winding 5, winding it of relay IR, and shoes 9 and 8 and the rail portion therebetween, to the minus terminal of winding 4. Windings It and H of relay IR are so arranged that the fluxes induced 0 therein by the film breakdown currents from windings 4 and 5 oppose each other, tending therefore to neutralize any torque due to these currents, thereby preventing operation of the relay on the film breakdown currents. As a fur- 45 ther precaution against undesired operation, relay IR should be so designed as to be immune to currents flowing from generator G.

Considering the track circuit source BX-CX however, it will be apparent that currents from this source flowing in windings 4 and 5 will set up opposing fluxes in the core of transformer T to neutralize substantially the impedance of windings 4 and 5 in the shunt path from rail I to rail 2, thereby aiding the release of relay TR.

Windings I0 and II of relay IR will, however, set up cumulative fluxes due to the track circuit currents from source BXCX, and if the shunt path from rail l to rail 2, the impedance of which is decreased by the flow of the film breakdown current, is sufficiently low in impedance, as determined by the release characteristic of relay TR, these track circuit currents will be of suflicient magnitude to pick up relay IR, thereby causing indicator L to become energized over front contact I2, to inform the car operator that the shunting apparatus is functioning properly to release relay TR.

If the condition of the rail surface is such that a satisfactory shunt may be obtained by a low impedance connection from rail to rail, without the use of the auxiliary voltage and current from generator G, the resistance film breakdown apparatus may be dispensed with, the indication relay IR being governed by the shunt current in the above-mentioned rail to rail connection in a manner similar to that when generator G is used.

It will, of course, be obvious that the apparatus embodying my invention is also applicable to direct current track circuits, use being made of a direct current relay IR in the latter case, the principles of operation being identical in both cases. If the car is to be used in territory wherein both alternating and direct current track circuits are installed, relay IR may be of the universal type, capable of operating on either direct, or alternating current of the track circuit frequency.

Although I have herein shown and described only one form of track shunting apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a rail vehicle and a section of railway track, a first source of track circuit current and a track relay for said section, a second source of varying current on said vehicle of such character as to be incapable of operating said track relay, a transformer on the vehicle having a primary winding energized from said second source and having two secondary windings each of which is connected across the two rails of said track by means of rail contacts, the instantaneous polarities of said contacts associated with either rail being opposite so that the voltages of said two windings aid each other in breaking down the resistance film on the rail surface to aid shunting of said track relay by said two windings, and an indicator on the vehicle incapable of responding to currents from said second source and having two windings connected respectively in series with said two secondary windings in such direction that the currents from said first source flowing from one to the other rail of said track through said indicator windings will aid one another, operating said indicator at or above a predetermined value of said currents.

2. In combination with a rail Vehicle and a section of railwa track, a first source of track circuit current and a track relay for said section, a second source of current on said vehicle of such character as to be incapable of operating said track relay, a plurality of circuits each of which applies a voltage from said second source across the two rails at separated points along said track for breaking down the resistance film on the rail surface to aid shunting of the track relay by said plurality of circuits, said circuits being inductively coupled in such manner as to minimize the impedance thereof to current from said first source flowing from one to the other rail of said track, and an indicator incapable of responding to current from said second source and having a plurality of windings, one included in each of said circuits, said windings being connected in such manner as to aid one another when carrying currents from said first source flowing in said circuits, said indicator becoming operated when the sum of said currents equals or exceeds a predetermined value.

3. In combination with a rail vehicle and a section of railway track, a source of track circuit current, a track relay operated by current from said source, a second source of current on said vehicle of such character as to be incapable of operating said track relay, means including a vehicle-carried track shunt for applying a potential from said second source to each rail of said track for breaking down the resistance film on the rail surface to aid shunting of said track relay by said track shunt, and indicating means on the vehicle immune to current from said second source and responsive in accordance with the magnitude of the current from said first source flowing in said track shunt.

4. In combination with a rail vehicle and a section of railway track, a wayside source of track circuit current connected with the track, a Vehicle-carried track shunt, a source of potential within said track shunt for breaking down the resistance film on the rail surface to aid shunting of the track by permitting current from said wayside source to flow through said track shunt, and means on the vehicle immune to current from said source of potential and responsive in accordance with the magnitude of the current from said wayside source flowing through said track shunt for indicating the effectiveness of said shunt.

HERBERT N. VAN AKEN. 

